package org.apache.lucene.analysis.standard;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;

import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.util.Version;

/**
 * Normalizes tokens extracted with {@link StandardTokenizer}.
 */
public class StandardFilter extends TokenFilter {
    private final Version matchVersion;

    /** @deprecated Use {@link #StandardFilter(Version, TokenStream)} instead. */
    @Deprecated
    public StandardFilter(TokenStream in) {
        this(Version.LUCENE_30, in);
    }

    public StandardFilter(Version matchVersion, TokenStream in) {
        super(in);
        this.matchVersion = matchVersion;
    }

    private static final String APOSTROPHE_TYPE = ClassicTokenizer.TOKEN_TYPES[ClassicTokenizer.APOSTROPHE];
    private static final String ACRONYM_TYPE = ClassicTokenizer.TOKEN_TYPES[ClassicTokenizer.ACRONYM];

    // this filters uses attribute type
    private final TypeAttribute typeAtt = addAttribute(TypeAttribute.class);
    private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);

    @Override
    public final boolean incrementToken() throws IOException {
        if (matchVersion.onOrAfter(Version.LUCENE_31))
            return input.incrementToken(); // TODO: add some niceties for the new grammar
        else
            return incrementTokenClassic();
    }

    public final boolean incrementTokenClassic() throws IOException {
        if (!input.incrementToken()) {
            return false;
        }

        final char[] buffer = termAtt.buffer();
        final int bufferLength = termAtt.length();
        final String type = typeAtt.type();

        if (type == APOSTROPHE_TYPE && // remove 's
                        bufferLength >= 2 && buffer[bufferLength - 2] == '\'' && (buffer[bufferLength - 1] == 's' || buffer[bufferLength - 1] == 'S')) {
            // Strip last 2 characters off
            termAtt.setLength(bufferLength - 2);
        } else if (type == ACRONYM_TYPE) { // remove dots
            int upto = 0;
            for (int i = 0; i < bufferLength; i++) {
                char c = buffer[i];
                if (c != '.')
                    buffer[upto++] = c;
            }
            termAtt.setLength(upto);
        }

        return true;
    }
}
